Chromosomal organization of amplified genes in multidrug-resistant chinese hamster cells

摘要: Six independently derived multidrug-resistant Chinese hamster cell lines selected with vincristine, daunorubicin, actinomycin D, or colchicine were probed by in situ hybridization techniques the cloned cDNA, p5L-18, to chromosomally localize known presumed amplified P-glycoprotein genes. One two clusters of genes demonstrable all highly resistant sublines and localized homogeneously staining regions and/or abnormally banding regions, gene amplification-associated cytogenetic abnormalities, on eight different chromosomes. Analysis trypsin-Giemsa banded karyotypes revealed additional, multiple chromosomal rearrangements that apparently nonspecific. Mapping studies native gene(s) region q23 31 (most probably band 26) long arm chromosome 1 normal bone marrow fibroblasts homologues cells. Southern blot analysis restriction endonuclease fragments indicated amplification one both (at least) wild-type nonallelic four presence line (DC-3F/DM XX) a unique 5.0-kilobase Bam HI fragment resulting from recombinational event during amplification. Comparison data no correlation between patterns generated Eco RI, Hind III, Pst I, location However, only which is positioned at 1q26 near site gene) exhibit either alterations structure regulation expression (DC-3F/AD X), suggesting process more complex than simply loco .